The present invention relates to trailer spraying devices of the type used in agriculture including a tank mounted on a frame of the device for holding a large amount liquid to be sprayed, a spray assembly mounted on the frame that is adapted to spray liquid from the tank in a predetermined pattern through a spray boom, and wheels rotatably mounted on the frame by which the frame is supported, which trailer spraying device is adapted to be coupled to a farm tractor and towed across a field as the liquid is sprayed from the device; the present invention being particularly related to the structure for mounting the wheels on the frame of such a trailer spraying device.
Well known in the prior art are trailer spraying devices of the type used in agriculture including a tank mounted on a frame of the device for holding a large amount liquid to be sprayed, a spray assembly mounted on the frame that is adapted to spray liquid from the tank in a predetermined pattern through a spray boom mounted on the frame that projects a long distance on both sides of the frame (e.g., up to 60 feet or 18 meters in both directions from the center of the frame), and wheels rotatably mounted along the sides of the frame by which the frame is supported. Such trailer spraying devices are adapted to be coupled to a drive assembly such as a tractor and to be towed across a field as the liquid is sprayed from the device through the spray boom. The tanks on such trailer spraying devices can carry a large amount of liquid (e.g., 1,200 to 1,600 gallons) which, together with the spraying assembly and other portions of the trailer spraying device, can cause the trailer spraying device to be very heavy (e.g., weigh over 18,000 pounds). Such trailer spraying devices have used two wheels, one on each side of the frame in the manner of a two wheel cart, which wheels have been very large in diameter (e.g., at least 60 inches (152 cm) or larger) and included large tires with lugs on their peripheries (e.g., 14.9R46 or 320/85 R38 tires) both (1) to provide the needed weight carrying capacity, and (2) to minimize the effect of passing over irregularities in a field, such as small ditches caused by erosion or narrow ridges, because a wheel dropping into or moving over such an irregularity can cause the projecting end portions of the spray boom to move up or down sufficiently to make an undesirable change in spray pattern being produced by the trailer spraying device. Despite the large size of such wheels, however, the weight of some such trailer spraying devices too easily causes the wheels to sink into soft earth, and ditches or ridges still cause an unwanted amount of pitching of the spray boom as the wheels pass through or over them.
The present invention provides an improved wheeled support assembly for a trailer spraying device of the type used in agriculture described above that includes a tank mounted on a main frame of the device for holding a large amount of liquid (e.g., 1,200 or 1,600 gallons) to be sprayed, and a spray assembly mounted on the main frame that is adapted to spray liquid from the tank in a predetermined pattern through a spray boom mounted on the main frame, which spray boom projects a long distance from both sides of the main frame (e.g., up to 60 feet or 18 meters in both directions from the center of the main frame). The improved wheeled support assembly according to the present invention provides greater weight carrying capacity by including two large wheels on each side of the main frame and also mounts those two wheels in a manner that reduces unwanted pitching of the spray boom as the wheels pass through ditches or over ridges compared to the pitching that occurs using only a single large wheel of the same size on each side of the main frame.
The wheeled support assembly according to the present invention includes a rigid wheel adapting frame fixed to the main frame, which wheel adapting frame comprises two elongate support members each spaced from a different one of the sides of the main frame to help provide wheel clearance spaces between those elongate support members and the sides of the main frame, each of which spaces is adapted to receive one of the wheels. The wheeled support assembly also includes two elongate pivot members, and means on each of the pivot members mounting two of the wheels on the pivot member for rotation about parallel axes transverse of the pivot member, one of which wheels is mounted on a first end portion and on one side of the pivot member, and the other of which wheels is mounted on a second opposite end portion of the pivot member and on its opposite side, with the parallel axes about which the wheels are rotatably mounted being spaced by a distance less than the diametrical dimensions of the wheels; together with means for mounting the center portion of each of the pivot members on a different one of the elongate support members for pivotal movement of the pivot member about an axis parallel to the axes about which the wheels are rotatably mounted with one of the wheels in the wheel clearance space, and the other of the wheels on the side of the elongate support member opposite the main frame.
Thus, the wheeled support assembly according to the present invention both provides two large diameter wheels (e.g., at least 48 inch or 122 cm diameter and preferably at least 60 inch or 152 cm diameter) on each side of the main frame to help distribute the weight of the trailer spraying device, and allows the axes of the wheels to be horizontally spaced a distance less than the diametrical dimension of the wheels (e.g., a distance in the range of 20 to 30 inches or 51 to 76 cm such as 24 inches or 61 cm), which allows the large wheels on the pivot members to move into and out of ditches or over ridges while restricting up or down movement of the projecting end portions of the spray boom and thereby restricting undesirable changes in the spray pattern being produced by the trailer spraying device. Also, mounting the large wheels on opposite sides of each pivot member causes the wheels to move along axially spaced paths which restricts localized compaction of the field along the paths of the wheels, and balances the load on the bearing by which the center portion of the pivot member is mounted on the elongate support member.